• Journal of the Korean Applied Science and Technology
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• v.33 no.1
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• pp.168-175
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• 2016

The surface of glass fiber bundle was modified with functionalized silanes and phenolic resin to improve the tensile strength as well as the adhesion of glass fiber to matrix phenolic resin. The surface modification of reinforcing glass fiber can play a significant role in controlling whole composite characteristics. We applied surface modification of glass fiber with two different functionalized silanes, such as glycidyltrimethoxysilane(G-silane) and aminopropyltriethoxysilane (A-silane), and phenol formaldehyde(PF) resin in one pot or separated process under different coating compositions and temperatures. Thermal treatment temperature is very important factor to improve the mechanical properties of modified glass fiber. Modified glass fiber bundle treated at $170^{\circ}C$ showed the highest tensile strength of $10.05g_f/D$. Surface analyses by scanning electron microscope(SEM) and FT-IR spectroscopy were used to characterize the surface coatings on glass fiber bundles. Mechanical property changes as functions of treatment conditions and coupling agent types were also explained.

• The Journal of the Korea Contents Association
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• v.7 no.3
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• pp.68-78
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• 2007

In a virtual aquarium, the behavior of fish objects is the most important factor in respect of visual effects. In addition to the individual behavior of fish object, the interactions between objects due to their attributes, can improve the dynamics and reality of the virtual world. In this paper, we analyze the principal habits of fish objects such as the vitality, the range of movement, the maximum depth of water they can live, and the cycle of eating. Then, we suggest a method for simulating the stable marine ecosystem with controlling the behaviors, the interaction with other species, the average span of life, and all that sort of thing based on the result of analysis. Because we can freely modify the behavior of fish object by altering the values of attributes, it can be utilized in the dynamic virtual aquarium, the 3D aquarium screen saver, and the virtual fish game, and so on.

• Human Ecology Research
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• v.55 no.4
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• pp.363-384
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• 2017

The Korean government implemented better support for adolescent single-parent families by expanding the coverage of the Single-parent Family Support Act in 2010. In order to understand the effect, this study verified the moderating effect of the single-parent family policy's support for child rearing in the context of adolescent female single-parent's stress levels and education sustainability. This study utilized part of the National Youth Policy Institute's 'Research on the Actual Condition of the Adolescent Pregnancy, Birth and Rearing Children'. Participants of the study were 248 adolescent single-parents aged 24 and below. The findings and discussion of this study are as follows. First, the stress level of adolescent female single-parent in continuing studies was lower than those for discontinued studies. Students who discontinued their education in the middle of studies showed an increase in life stress level relative to age because they had a low level of education and had discontinued studies before pregnancy. Second, the public nanny service has been verified as an element to increase the continuation of education by controlling the level of stress. It is advisable to fortify and expand the scope of support for childcare services in the form of a study assistant or child education assistant. Last, adolescent single-parent childcare subsidies have been verified as a direct factor that raised the meaningful level of education continuity potential to a meaningful standard that can be seen as a more effective method than general policy support for single-parent families.

• Korean Journal of Social Welfare
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• v.47
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• pp.206-242
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• 2001

A survey research was conducted for a sample of 306 adult children who have an elderly parent or both parents alive. The purpose of the research was to test a structural equation model which specified the effects of early family relationships on comtemporary relationships and assistance patterns between adult children and their parents. The data were analyzed using EQS for Windows 5.7, utilizing maximum likelihood method. The results showed that early family relationships affected filial concern first, which in turn affected the level of assistance provided by adult children for elderly parents. No direct effect has been found between early family relationships and the level of assistance by adult children for elderly parents. Filial concern was played as an intervening variable. Early family relationships gave no direct effects to adult children's intention to assist their parents. Here again, filial concern was played as an intervening factor. Adult children's intention to assist their parents had not been led directly to provision of actual support to parents by their adult children. Thus, it was identified that intention to support is one thing, and the actual support is another. Controlling for the effects of filial concern, overall, early family relationship patterns gave no differential effects to the different aspects of support provided to parents by their adult children. On the basis of these results, this paper provided both discussions and suggestions for some strategies of intervention in the present family relationships in order for the inter-generational exchange of supports to happen in the future.

• Geotechnical Engineering
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• v.14 no.1
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• pp.93-108
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• 1998

In this study, the analytic solutions and numerical methods were used to estimate the shape and size effects on the stability of underground openings. The stability of underground openings was evaluated by scrutinizing the effects of the rock mass quality, the state of in-situ stresses and the lateral earth pressure coefficient on the displacement, the stress concentration and the plastic region developed in the vicinity of the openings. The analytic solutions have shown that the stress concentration factor is inversely proportional to the radius of curvature of openings. Through parametric study on the various shapes and sizes of underground openings the characteristics of the controlling factors concerned with the stability were analyzed. Then, the study was extended to the horseshoe-shaped openings commonly used for under ground storage. Through the extended study the effects of the stress ratio and the height-towidth ratio of openings on the maximum displacement and plastic region developed around the openings were estimated. The results have shorn that the height-to-width ratio of domestic storage caverns can be increased economically without stability problem, as far as the lateral earth pressure coefficient is appropriate.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.303-310
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• 2002

Overbreak occurred inevitably in a tunnel excavation, Is the main factor for increasing cost and time in tunnel projects. Furthermore the damage to the remained rock mass related to the overbreak can give rise to a serious safety problem in tunnels. As a rule of thumb, causes for the overbreak are inaccuracy in drilling, the wrong design of blasting and selection of explosives, and heterogeneity in rock mass. Specially, the geological features of the rock mass around periphery of an excavation are very important factors, so a lot of researches have been conducted to describe these phenomena. But the quantitative geological classification of the rock mass for the overbreak and the method for decreasing the amount of the overbreak have not been established. Besides, the technical improvement of the charge method is requested as explosives for the smooth blasting have not functioned efficiently. In this study, the working face around periphery of an excavation has been continuously sectionalized to 5∼6 parts, and the new Blastability Index for the overbreak based on 6 factors of RMD(Rock Mass Description), UCS(Uniaxial Compressive Strength) JPS(Joint Plane Spacing), JPO(Joint Plane Orientation), JPA(Joint Plane Aperture) and FM(Filling Material) is proposed to classify sections of the working face. On the basis of this classification, the distance between contour holes and the charging density are determined to minimize the overbreak. For controlling the charging density and improving the function of explosives, the New Deck Charge(N.D.C) method utilizing the deck charge method and detonation transmission in hole has been developed.

• Journal of the Korean Institute of Navigation
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• v.10 no.2
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• pp.97-114
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• 1986

Ship's maneuverability is very important factor in safe ship handling and economical ship operation. Steering characteristics are consisted of course stability and maneuverability. Today in many advanced ship-building countries, they study ship's course stability, using model ship tests, such as straight line tests, rotating arm tests and Planar Motion Mechanism (PMM) etc., in tow in tanks. It is the purpose of this paper to provide ship's handlers with better understanding of steering characteristics and to help them in safe controlling and manevering . In this paper, the author simulated response of various vessels, running straight course with constant speed, and they are disturbed by small external disturbance of one degree yaw angle with no angular velocity . The author used the hydrodynamic derivtives resulted at tests of Davidson's laboratory in Stevens Institute of Technology, New Jersey, U.S.A. Course stability was evaluated and analyzed in various respects, such as block coefficient, ratio of ship's length to beam, draft and rudder area ratio etc. The obtained results are as follows : (1) The ship's course stability is affected by magnitude of block coefficient greatly. In case that the block coefficient is more than 0.7, the deviation varies at nearly same rate but the requistite time to reach the steady course is different. (2) The ship's course stability is affected by magnitude of L/B. When the dimensionless time reaches about 3, the deviation and requisite time to reach the steady course are influenced nearly same. After the dimensionless time is about 3, they change on invariable ratio. (3) The effect to course stability by L/T and RA' can be neglected. (4) The reason why thy VLCC and container feeder vessel are unstable on their course is that their block coefficient is generally more than 0.8 and the ratio of ship's length to beam is about 6.0.

• Resources Recycling
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• v.16 no.6
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• pp.20-27
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• 2007

This paper presents a detailed experimental study on the durability properties of mortar matrix made with two kind of recycled fine aggregates(RAA, RAB) and five replacement levels (0, 25, 40, 75 and 100) of the recycled fine aggregates as a partial replacement of natural fine aggregate (NA). The durability properties of mortar matrix was evaluated using compressive strength, chloride ion ingress, sulfate attack and carbonation. The test results indicated that the water absorption and Adhered mortar of the recycled fine aggregate was a major factor controlling durability properties. Hereafter, when using built recycled fine aggregate is expected, appropriate removal Adhered mortar and reasonable replacement ratio of recycled fine aggregates was 25% weight of cement are advised to apply to the concrete materials.

• Journal of Construction Engineering and Project Management
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• v.10 no.1
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• pp.16-32
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• 2020

Cost and time control of projects is important in preventing project failure. However, achieving effective cost and time control in practice is often challenging. The challenges of project cost and time control in practice are investigated by carrying out a questionnaire survey on the top 150 construction contractors in the UK followed by in-depth semi-structured interviews of practitioners from 15 construction companies in the country. Quantitative analysis reveals that design change is the most important factor inhibiting the ability of UK contractors from effectively controlling both the cost and time of construction projects. Four of the top five factors inhibiting effective cost control are also the top factors inhibiting effective time control albeit in a different order. These top factors-design changes, inaccurate evaluation of project time/duration, risk and uncertainty, non-performance of subcontractors and nominated suppliers were also found to be endogenous factors to the project. Additionally, qualitative analysis of the interviews reveals 16 key challenges to prevent for effective project cost and time control in practice. These are classified into four categorised based on where they stem from as follows; from the organisation (1. Lack of integration of cost and time during project control, 2. lack of management buy-in, 3. complicated project control systems and processes, 4. lack of a project control training regime); from the construction management/project management approach (5. Lapses in integration of interfaces, 6. project control not being implemented from the early stages of a project, 7. inefficient utilisation and control of labour, 8. limited time devoted to planning how a project will be controlled at the outset); from the client; (9. Excessive authorisation gates, 10. use of adversarial and non-collaborative forms of contracts, 11. communication problems within client set-up, 12. obstructive client representatives) and; from the project team (13. Lack of detailed/complete design, 14. lack of trust among the project partners, 15. limited time devoted to project control on site, 16. non-factual reporting). The study posits that knowledge of these project control inhibiting factors and challenges is the first step at ensuring they are avoided and enable the implementation of a more effective project cost and time control process in practice.

• Journal of Environmental Health Sciences
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• v.35 no.1
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• pp.36-44
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• 2009

Hand-washing has been recognized as a critical factor in controlling infection and cross-contamination. This study was performed to investigate hygienic behavior of male university students focusing on awareness of hand-washing, their hand washing practices, and the difference between their awareness and practices. Both a self-administered questionnaire survey and a separate direct observation in restrooms were carried out at a university campus over a four week period. In the survey, 93.6% of the responded students claimed to wash their hands after using toilet. However, just 16.9% of the observed students actually did so, according to a separate and unnoticed observational study. Among the observed students who washed their hands, 25.0% of them used soap, only 5.0% of them washed four parts of their hands, and 15.0% of them washed their hands for more than 10 seconds. Paper towel was the most common hand drying method in the direct observation and also in the survey. Significant differences between the questionnaire survey and the direct observation (p<0.0l) were found in hand-washing practices, duration of hand-washing, using soap, washing parts of the hand, and hand-drying method after using the toilet. This study indicates that there is a remarkable difference between the male university students' awareness of hand-washing and their hand-washing practices. This study reveals that there is the need for programs or campaigns to increase hand-washing practices of male university students.